If double click on file won’t open Microsoft Excel or will open Excel application but [ can't open file error ] will occur then we have the following resolution 100% successfully tested on Windows XP with Microsoft Office 2003  ver.11.0.5614.0 Service Pack 2.

• Open Microsoft Excel > Tools > Options > General > under Settings
• Uncheck < Ignore other applications >
• Start > Run > type: “c:\Program Files\Microsoft Office\Office11\Excel.exe” /unregserver
• Restart machine
• Start > Run > type: “c:\Program Files\Microsoft Office\Office11\Excel.exe” /regserver